1. Field of the Invention
The present invention relates to a semiconductor film, an oxide microparticle dispersion liquid, a method for manufacturing a semiconductor film, and a thin film transistor.
2. Description of the Related Art
A transparent oxide semiconductor (TOS) which is transparent, has high mobility, and has excellent manufacturing suitability attracts attention, and thus a transparent oxide semiconductor reaches a level of a practical application as an active layer of an oxide thin film transistor (TOS-TFT) in some cases. An active layer in TOS-TFT which is practically applied now is manufactured by a vacuum film deposition method. However, since a manufacturing cost easily increases in a case of the vacuum film deposition method, research of aiming at the realization of TOS exhibiting excellent characteristics by a solution applying process is vigorously conducted in some cases.
As a method using such a solution as a raw material, a method of applying a solution raw material including metal alkoxide, an inorganic metal salt, or the like, applying some energy, forming a network of metal and oxygen, and converting a solution with the network into an oxide semiconductor and a method of dispersing oxide semiconductor microparticles in which a network of metal and oxygen are formed in advance in a solution and applying this solution so as to obtain a TOS film consisting of an aggregate of microparticles are considered.
For example, it is reported that electroconductivity is enhanced by substituting a ligand molecule bonded to a quantum dot (for example, in the range of 2 nm to 10 nm) with a shorter ligand molecule (for example, “Structural, Optical, and Electrical Properties of Self-Assembled Films of PbSe Nanocrystals Treated with 1,2-Ethanedithiol” ACS Nano (2008) written by J. M. Luther, et al.).
In addition, a method of forming an oxide semiconductor thin film by using a nanoparticle dispersion liquid including metal oxide nanoparticles which are selected from the compound including special metal and which have an average particle size of 50 nm or less and a dispersion medium is disclosed (for example, see JP4738931B).
In addition, a technique of forming a microparticle layer by applying a dispersion liquid in which microparticles are dispersed to a substrate is disclosed (for example, see JP2010-80689A, JP2013-112594A, and JP2008-130703A).